PROTEIN REFOLDING IN AN
OSCILLATORY-FLOW-MIXING REACTOR

C.T. Lee and A.P.J. Middelberg*<=
/sup>

Department of Che=
mical
Engineering, University of Cambridge, UK

We demonstrate that an oscillatory flow-mixing
reactor (OFMR) operating in fed-batch mode is viable for industrial protein
refolding.OFMR offers the
advantage of uniform, controllable, and scalable mixing.Denatured lysozyme (15 mg/ml, in =
8 M
guanidine hydrochloride (GuHCl) or 8 M urea, and 32 mM dithiothreitol) was =
fed
into a 150-ml OFMR for 2 h and the final solution was incubated for a furth=
er 3
h.A control experiment used=
a
small perfectly-mixed stirred-tank reactor (STR).Both systems were operated under mild and intense mixing
conditions.With GuHCl
denaturation, the refolding yield profiles throughout the 5 h period were
identical in both the OFMR and STR, and yield was independent of mixing
intensity.Conversely, refol=
ding
yield in both reactors following urea denaturation decreased from 25% to 15=
% as
mixing intensity decreased.Clearly, imperfect mixing in large STRs may lead to reduced refolding
yield when urea is used as a denaturant.&=
nbsp;
This effect can be minimised by using a reactor with uniform,
controllable and scaleable mixing, such as the OFMR.